Circulation Skills 2:
Central Venous Access
Indications
- A peripheral IV cannot be established rapidly, and IV access is urgently needed.
- Volume resuscitation is being conducted in a patient at risk for overload. Ecclampsia patients, traumatized pregnant patients, geriatric patients, and severely burned patients with pulmonary injuries are examples.
- Central access is needed for transvenous pacing.
Complications
Pneumothorax, arterial puncture, the cannula goes up the internal jugular vein instead of the superior vena cava, the cannula goes into the pleural space and fluid is infused, air embolism occurs.
Choice of approach
In severe hypovolemia, even the central veins can collapse. The Trendelenburg position helps by filling these veins and also by reducing the risk of air embolism. A substernal thyroid gland can distort anatomy significantly. No approach works all of the time, so physicians may use any of these. A good rule is to give your first choice three tries, then move on to another approach.
Equipment
- A single lumen 8.5 French sheath introducer (Trauma kit provided by Arrow, Int.) is most useful in the rural setting. The Trauma kit is inexpensive and provides an excellent route for administering blood and other fluids.
- Triple lumen Seldinger technique catheters are useful in medical cases when IV meds are needed in addition to fluids.
- Central venous pressure saline manometer.
Technical points for all routes
- Do not apply constant suction on the needle as you search for the vein. You will plug the needle with fat.
- Listen for irregular beats on the ECG monitor when the guidewire is advanced. If PVCs occur, pull back the guidewire.
- The guidewire must always be held or kept in view, or it can be inadvertently lost in the circulation. See Vol II—Circ Skills 1 Arterial and Venous Catheter Insertion for more on the Seldinger technique.
- If you puncture the subclavian or carotid artery with your exploring needle, simply withdraw. The artery will seal itself. If, however, you insert an introducer and then discover it is intra-arterial, leave it in place. Consult surgery. An operating room will have to be ready when the device is pulled and an attempt made to tamponade the site. Fatal hemorrhage may result if the operating room and equipment is not ready.
- Be aware of the danger of air embolism. Always place the patient in Trendelenburg position. Suture the catheter in place and make sure that the IV connections are securely locked together. Remember the treatment for air embolism. Roll the patient to his or her left side with the head down so the air stays in the right side of the heart. Listen for heart sounds, and you will hear Hamman’s crunch. Aspirate blood and air from the right heart. Administer oxygen. If cerebral signs are present, hyperbaric oxygen treatment is indicated. Myocardial ischemia may also occur. Air embolism gets worse in decreased atmospheric pressure, so air transport may be problematic.
- PEDS: In infants and small children, 30 degrees of Trendelenburg is recommended to fill the central veins. The anatomic landmarks and needle directions are the same as with adults.
Infraclavicular subclavian approach
Always maintain the needle parallel with the floor. If it runs into the clavicle, push the whole needle posteriorly rather than trying to angle the needle under the clavicle; angling the needle causes pneumothorax. If the needle goes into position but no blood returns, try the next stick with the needle directed more toward the larynx than the suprasternal notch. Pulling down on the arm may bring the subclavian vein closer to your needle. The needle should go under the clavicle at the junction of its middle and medial thirds.
It is easier to keep the needle parallel with the floor if the skin is punctured several centimeters inferolateral to the point where the needle will go under the clavicle. If you aspirate air, the lung has been penetrated and a pneumothorax is now present. If the patient will not be under drapes in the operating room and will not be put on a respirator, a small guidewire-assisted chest tube may be inserted.
Three views of the infraclavicular approach:
(A)
The needle enters the skin lateral to the junction of the medial
and middle thirds of clavicle, then goes behind the clavicle at that
junction.
(B) The
needle is aimed at the suprasternal notch.
(C) The
needle is kept parallel with the floor to prevent pneumothorax.
The patient is in slight Trendelenburg position.
Supraclavicular subclavian approach
The anterior scalene muscle separates subclavian vein from the subclavian artery. This muscle forms the floor of the notch you feel at the lateral border of the SCM and the clavicle. You will encounter the vein within 1 to 3 cm of puncture or not at all, so do not go deep.
The patient is in Trendelenburg position. Direct the exploring
needle
toward the contralateral nipple in the notch formed by the muscles.
Internal jugular approaches
- Anterior approach to the internal jugular vein between heads of the SCM. You will encounter the vein within 1 to 3 cm of puncture or not at all, so do not go deep. Direct the needle inferiorly. Direct the exploring needle (with an attached syringe) posteriorly-inferiorly through the mid-portion of the SCMtriangle.
A
B
- Posterior approach to the internal jugular vein behind the muscle belly of the SCM. You will encounter the vein with 1 to 3 cm of puncture or not at all, so do not go deep. When a patient’s anatomy interferes with other approaches, this one still works. Keep the needle against the posterior aspect of the SCM to avoid the carotid artery. With the patient in Trendelenburg, direct the exploring needle under the SCM, keeping it against the undersurface of the muscle belly.
 An 8.5 F introducer is most useful when volume infusion is most important. |
 A triple lumen introducer is most useful when a route for medications is most important. |
PEDS: In small children weighing less than about 10 kg, a 5 French double lumen introducer, 5 cm long, is most useful (Cook Critical Care). It uses a 22 ga exploring needle. The lumens are 20 ga equivalents. Introducers 8, 12, and 15 cm are available for children weighing 10 to 40 kg. The 8 cm length is for internal and external jugular approaches. The 12 cm length is for the right subclavian approach. The 15 cm length is for the left subclavian approach.
Taking care of and removing central lines
- Air embolism is a great risk while inserting, taking care of, and removing central lines. Even a single bubble of air can reach the brain or coronary arteries when the patient has a patent foramen ovale. This is not uncommon, and most patients are unaware of its presence. If the foramen ovale is closed and no other right to left shunts are present, a bubble of air can be injected into the veins. This small quantity of air is trapped in the pulmonary circulation and is gradually dissolved. However, if the load of air is large, it accumulates in the right ventricle where it interferes with the pumping action of the heart. The patient is essentially in cardiac arrest at this point. Also, some of the air is ejected, and it goes through the pulmonary circulation into the left side of the heart. Air is then ejected into the cerebral and cardiac circulations. A seizure or cardiac dysrhythmia may be the first manifestations of air embolism. If one listens for a heart beat, Hamman's crunch may sometimes be heard. This is the sound of splashing blood in the right heart. It was originally described in mediastinal emphysema.
To prevent this disaster, do the following: (1) place the patient in the Trendelenburg head down position when inserting or removing the line; (2) Tell the patient not to breathe while the catheter is being placed or removed. A gasp causes air to be sucked into the needle or cannula, even in the Trendelenburg position; (3) Keep the needle hub and the catheter ports covered as much as possible; (4) Make sure that all the IV line connections are firmly in place and secured; (5) Caution the patient about loosening their lines or moving about causing the lines to become disconnected; and (6) Use occlusive dressings over the removal sites because an open track can lead to the vein.
If air embolism occurs, immediately turn the patient onto the left side so that air tends to be trapped in the right ventricle. Put the patient in steep Trendelenburg position, which also keeps the air in the ventricle. If a central line is in place, attach a large syringe and attempt to aspirate air. If the patient is obtunded, intubate the patient and administer 100% oxygen. If the patient is aware, attach a non-rebreathing mask and administer 100% oxygen. If cerebral manifestations have occurred, such as a seizure or obtundation, immediately arrange for transfer to a hyperbaric chamber for bends (decompression illness) treatment. In any case, call for a consult from a diving medicine physician. Transfer via helicopter or airplane may be detrimental because of the reduced gas pressure at altitude. A low altitude flight may be necessary.
- Cardiac dysrhythmia and even ventricular fibrillation can occur if the guidewire touches the heart. Always attach a cardiac monitor to the patient when inserting central lines. If a premature ventricular contraction (PVC) is heard during insertion, pull back the guidewire before proceeding. An external cardiac defibrillator should be available.
- Uncontrolled bleeding can occur if the cannula is inserted into an artery in an anatomic position that is not compressible. An exploring needle is small enough that the puncture site is occluded by the arterial smooth muscle. So, if pulsatile flow returns through the needle, remove it and the site will seal itself. However, if the patient is very hypotensive or in cardiac arrest, pulsatile flow may not be seen. If an introducer is inserted into the artery and it is discovered later that it is in the subclavian or carotid artery, do not remove it because you will not be able to provide direct compression to the site of puncture. Leave it in place and consult your surgical back up. A thoracotomy may be necessary to provide compression. A puncture of the carotid artery may require direct surgical repair.
Reference
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Dronen SC, Younger JG. Central venous catheterization and central venous pressure monitoring in Clinical procedures in emergency medicine, 3rd ed. Roberts JR, Hedges JR eds. Philadelphia, WB Saunders, 1998;358-385.